Active-duty gay and lesbian service members are quietly building an underground support network at U.S. military outposts around the world, anticipating that "don't ask, don't tell" will be repealed.

As Congress weighs a Pentagon review of the military's policy banning openly gay service members, the network, known as "OutServe," revealed Monday that it has nearly 1,300 members across 27 chapters in 15 states, the military service academies and 10 foreign countries, including Iraq and Afghanistan.

While the numbers likely represent a small fraction of closeted gays and lesbians in the armed forces, they shed light for the first time on the extent to which many are organizing, predominantly through social media but also in secret in-person meetings and conference calls.

"Of all the support organizations the military brings to the table, this one can address our needs," a gay Air Force master sergeant who facilitates the OutServe chapter in Afghanistan said. "We are not able to freely communicate our specific issues with any of them in an open manner."

The serviceman, who asked to be identified only as Charles for fear of being thrown out of the military, is stationed at the International Security Assistance Force headquarters in Kabul, Afghanistan. He said most of his chapter's 50 members are scattered throughout the rugged country, from small combat outposts of 100 people to larger military bases in Kandahar and Baghram.

"We communicate mainly through Facebook, I pass on current news from the states and they pass on any concerns, if any they have," he said. "The Facebook page has also become a way for our troops to find out who is where and organize some small social get-togethers."

The online group is strictly limited to active duty personnel to protect their identities.

"Meeting face-to-face and knowing there is someone else like you out there is a huge morale builder," Charles said.

J.D. Smith, pseudonym for an active-duty Air Force officer who founded the network in July, said he envisioned a counterpart to a similar British organization -- known as "Proud 2 Serve" -- that helped facilitate integration of openly gay troops into the U.K. military 10 years ago this month.

"When a repeal does occur and a commander wants to learn more or get in touch with gay and lesbian service members, we can be that resource," said Smith, who is about to deploy to Afghanistan with his unit.

Closeted Gay Troops Join Secret, Worldwide Network

Until the policy changes, however, OutServe does not expose the names, ranks or identities of its members. But Smith said members hail from all five military branches and include a mix of officers and enlisted men.

The largest chapters are Southern California, with 110 members, and Germany, with 85 members. More than 50 gay troops serving in Iraq and Afghanistan have also formed a chapter.

"We have a huge influx of Marines joining right now," Smith said.

A Pentagon review of "don't ask, don't tell" released Tuesday noted that concerns about a repeal of the policy are highest in the Marine Corps, with 43 percent of Marines opposed to letting gays and lesbians serve openly, compared with 30 percent for all service members.

But the report also said "the risk of repeal of 'don't ask, don't tell' to overall military effectiveness is low."

Advocates for gay and lesbian service members are hopeful the Senate will approve a conditional repeal of "don't ask, don't tell" before the end of the year, which is widely viewed as the last, best chance for the foreseeable future.

The House approved a defense spending bill that included a repeal provision in September. But several high-profile Senate Republicans, including Sen. John McCain, have vowed to block any attempt at lifting the military gay ban.

Meanwhile, the policy faces several ongoing constitutional challenges in federal court. In October, a district court judge in California ruled "don't ask, don't tell" unconstitutional and barred its enforcement. An appeals court later reinstated the military's gay ban while the case is pending.

"You hear President Obama say we want to pass this policy so that people who want to serve can serve," Smith said. "But people forget there's a bunch of us serving right now."